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Questions tagged [iterator]

An iterator is an object-oriented programming pattern which for the most part functions similarly to a pointer to an object inside a collection with the added ability to traverse through the collection in a defined manner, agnostic of the actual implementation or even object addresses in physical ...

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2answers
69 views

Finding the common iterator category in C++

I created a template trait which finds the common iterator category between a set of given iterator categories. More specifically, it's a class with a member type alias to one of the iterator tags ...
2
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1answer
32 views

Finding the Original Fractions from Rounded Decimals

The data I'm using is summoning rates from a gacha game, One Piece Treasure Cruise. The game provides the probability of getting a certain character in percents rounded to the nearest thousandth. ...
6
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1answer
77 views

Walking directory tree like python does

I like python's os.walk and I was missing it in C#. It's a very convenient API so I thought I create my own utility that does something similar. The original API ...
4
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1answer
65 views

back_inserter for several container arguments

Recently I wrote a back_inserter with the same interface as the std::back_inserter just for supporting several containers in the constructor and doing push_back for each. The solution needs C++17. ...
1
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1answer
34 views

Convert a type u16 number to a matrix (Vec<Vec<u8>> or array) of 4 x 4

I am a Rust newbie and I am not familiar with all the iterator options. This is what I have so far. How can I make this better or at least avoid collecting twice into a Vec? ...
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1answer
54 views

Check if an element exists in a list of dictionaries [closed]

The logic of the code to build was as follows, two logical conditions; If the value of dictionary element matches in the list of dictionaries return the particular dictionary, and if no element ...
4
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1answer
100 views

Reverse C++11 range-based for loop

I wrote this snippet: ...
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0answers
32 views

Deferred Iteration in TypeScript

I've published a new TypeScript library currently in beta, and was hoping to get feedback on certain aspects of it, particularly implementation details for improving the performance of deferred ...
6
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1answer
57 views

General nested for

I needed a general-purpose function that accepts some sequence_container<sequence_container<T>> and iterates all permutations of the inner container. To ...
6
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3answers
117 views

Progress bar wrapper class in C++

I've recently written a simple progress bar class in C++ to mimic usage of similar libraries I've used in Python. The idea is to take some iterable container (e.g. ...
4
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4answers
743 views

Take a desired string, iterate through objects to see if it exists in a given field and append a number until a unique string is found

I wanted to in the most generic way possible write a method in C# to achieve the following. Take in a string, a set of objects, and a function to access the field of a given object Look at all of the ...
2
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1answer
87 views

Handling related generic type parameters

In answering a question on StackOverflow, it occurred to me that a more generic version of GroupBy for C# that delegated membership in each group to a class could ...
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1answer
48 views

putting sql-query response directly to foreach-loop?

Is there any reason to not do this? Putting the query directly inside a foreach-statment when the only time the result is going to be used is within that location.. ...
10
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4answers
801 views

Basic iterator supporting vector implementation

On the fly, I just implemented this iterator supporting vector class to understand how range-based for loop works. It's really basic but let me know what can be improved. Vector.h ...
7
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3answers
130 views

Endless stream: stream a range and return default value if the range is exhausted

Introduction: Motivation Sometimes there is a need to merge N > 1 ranges, and they don't have equal length, but there is a value which can be used in case the range is already exhausted. It is ...
7
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3answers
1k views
7
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2answers
212 views

Iterator for BFS binary tree traversal

I implemented an iterator pattern for C# using IEnumerator and IEnumerable. The goal of the implementation is to traverse a ...
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0answers
43 views

Identifying objects as some type of enum

Please review my code. It works as it should but I think about making it more pretty or optimal. This method should take in some IEnumerable of ...
5
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2answers
63 views

Iterable object on set of ids

For some of the algorithms that I am implementing it turned out to be useful storing ids in order to iterate on objects, while also avoiding having to think about reallocation and invalidation of ...
1
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4answers
178 views

Implementing a custom iterator by inheriting from an existing iterator class and overriding operator*

My goal is to write very little code and I want a custom iterator that only changes the behavior of the dereference operator* but copies the rest of the behavior ...
4
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1answer
54 views

General use multi-dimensional container using operator[]

This is a followup to a previous question of mine on same subject. Context I want to have a tool that allows to simulate as much as possible a C++ standard container for a multidimensional ...
6
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1answer
362 views

Getting serial port list

Needed to get a local serial port list. System.IO.Ports.SerialPort.GetPortNames() returns names but not the descriptions like you can see in Device Manager: ...
3
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1answer
108 views

Flatten nested iterables

I wrote a program sometime ago that reads csv files, sorts, reorders and groups their columns/rows' content (with itertools) and later labels the groups using a ...
9
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2answers
175 views

Multi-dimensional container using operator[]

This is a late followup to a previous question of mine on same subject. Context: I want to have a tool that allows to use all the C++ goodies (algorithms, for loop on containers, etc.) on a ...
2
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1answer
63 views

Implementation of generic unordered list in java

This question is a follow-up question of this question. These features are added to the new class - Generic class User is capable of setting the size ...
5
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2answers
228 views

Generic in order traversal iterator for binary trees

This actually started off as member type for the binary_search_tree, but after realizing that it doesn't compare to values or use the value objects inside of it, I ...
7
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2answers
56 views

Acts like an iterator, but counts

I’m making a “counting iterator” which emulates a constant container of consecutive values of some integral type. It is mostly boilerplate, going through the list of requirements for different ...
7
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1answer
73 views

Custom container for iterating over combinations of elements from multiple sets

Motivated by some SO quesitons [1, 2] I made an attempt at implementing a custom container with a bi-directional custom iterator for iterating over all combinations of elements from multiple sets. I ...
9
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2answers
700 views

Determine added, removed and kept items between two lists

My code is determining the difference between two iterables in terms of items that have been addded, removed and kept. The items are assumed to be sortable and there are no duplicates. ...
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1answer
95 views

Poor decision of IEnumerable of IEnumerable of IEnumerable [closed]

I wish to improve a class design that causes me readability and performance problems as the code grows. ...
18
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8answers
2k views

Counting elements meeting a predicate in an enumerable without iterating the entire sequence

I was reading this question, and the answer that mentioned streams, and a thought had occurred to me. In many cases (at least in my usage) I want to determine if a sequence (or ...
6
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1answer
69 views

Iterator over a container with indexing operation

This is a random access iterator that stores an index and a reference to a container. It iterates over any container with indexing operation. It does not have copy assignment / move assignment ...
8
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2answers
308 views

Parsing oscilloscope binary data file with C++

Preliminaries I have OWON oscilloscope that is able to record waveform in file in three formats: Text format .txt: the first lines are some general information ...
2
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0answers
94 views

Iterator for custom List class

I have extended a custom list class I have been working on with a Iterator class. I have not used std::iterator as a base class as it will be deprecated in C++17. ...
10
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2answers
602 views

Custom C++ random access iterator for pointers to arrays

I have implemented a custom iterator to iterate over an array that is held by a pointer. The iterator accepts a unit which specifies by which amount the underlying pointer is increased (or decreased) ...
3
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0answers
182 views

Helper trait for modularizing iterator chains which involve grouping items in tuples

The itertools::Itertools::tuples method from the itertools crate appears to be limited in the aspect that the trait ...
4
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1answer
86 views

Lazy lists with transformations, using generators & iterators

I built this very-basic lazy list (I'll add more methods as I need them). You provide it an array, a generator or any iterator. It creates a lazy list, which lets you run a pipeline of transformations ...
6
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3answers
585 views

Compute Convex Hull

The question asks to compute the convex hull of a set of 2D points. A convex hull is basically a series of consecutive line segments that suffice to enclose all the points in the area. In this ...
5
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1answer
1k views

Check if multiple lists contain an element from a large external list

I have a list of lists (many tokenised sentences). For anyone who doesn't know what tokenised sentences are, my list is like so: ...
3
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2answers
448 views

Example of adding STL iterator support to custom collection class

I'm trying to create an example of a custom collection with an API meeting the requirements of STL iterator templates, as a learning experience. The collection used here, a ring buffer, is merely a ...
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0answers
34 views

Using Generators for private scope

There's something about this code that's pretty neat-o to me, but is it a bad idea? Is there a name for programming like this? First, the generator itself: ...
5
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1answer
102 views

C++ container — variable byte coded numbers list

I'm writing a container for unsigned integers, which uses variable byte coding. It works but some decisions I took look ugly so I would be glad if you gave me some hints for improving the design. I ...
1
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3answers
337 views

Merge sorted lists, removing duplicates

I want to merge two sorted lists of Integers but this is not the general mergesort case because the same number may appear in both lists. (However, each number can only appear once in a particular ...
3
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0answers
119 views

Implementing a tabular pretty-print using Java 8 Stream API

About six years ago I implemented a simple tabular pretty-print Java class that mostly simulated MySQL CLI query result tables. I don't really like it because it was implemented in a, I believe, ...
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1answer
79 views

Retrieving synonyms from an ontology

My question is about my Ontology which retrieves synonyms from the ontology by using isSynonymOf object property. (Note that my Ontology file is 260 kb and expected to become 500kb). I am ...
8
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2answers
351 views

Lazy split and semi-lazy split

Sometimes I need to be able to split data into chunks, and so something like str.split would be helpful. This comes with two downsides: Input has to be strings You ...
3
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0answers
36 views

Apply arbitrary action during recursive generator function

I've got this recursive generator function. It will traverse an object looking for "leafs", any keys that don't point to sub-objects. Then it applies one of two actions on the leaf and yields it. Any ...
9
votes
1answer
763 views

Merge n sorted iterators

Over the weekend I was curious about efficiently merging multiple sorted iterators together, and for them to be in sorted order. This is quite like a challenge on HackerRank: You’re given the ...
6
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2answers
171 views

Iterator of Container of Container

Based on this question I though I would pull together an iterator that iterated over a container of containers. ...
10
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3answers
1k views

Table of Tribonacci sequence using NumPy and PANDAS

What I am trying to accomplish is calculate the Tribonacci numbers and the ratio. I can do this in Excel easy like this. So I tried do the same using Python 3 now. It works and gives such output. ...